Telephone system



Dec. 9, 1924. 1,518,736

f c. l..l GooDRuM TELEPHONE SYSTEM Filed Deo. 2, 1920 //7 Ven/0h @har/e5 @ood/w77.

Patented Dec. 9, 1924i UNITED STATES .Parent narici.,

CHARLES L. GOO'DRUM, OF NETN YORK, N. Y., ASSGNOR'TO WESTERN ELECTRIC C0 J.-

PANY, INCORPORATED, O1? NEW YORK,

N, Y., A GORPO'RATION OF NEEV YGRK.

TELEPHONE SYSTEM.

Application filed December To all whom it may conce/m.'

Be it known that l, CHARLES L. GoonnUM, a citizen of the United States, residing at New York, in the county ot New York, State of New York, have invented certain new and useful Improvements in Telephone Systems, ot which. the following` is a full, clear, concise, and exact description.

This invention relates to telephone systems, and more particularly to such systems adapted for paging or dictating` purposes.

An `object oi the invention is to provide improved and simplilicd means whereby any one of av plurality of calling stations r may selectively call any one of a plurality ot' loud speaking stations. By Athe term loud speaking stations is meant a station equipped with a loud speaking receiver and a transmitter.

To attain the above mentioned object the invention contemplates extending each of the calling, and each of the loud speaking stations over three conductors to a central point, at which point automatic switches controlled from calling stations are provided for extending a connection from a calling station to a loud speaking' station. Each calling station may be provided with an impulse sender for directively setting numerical switches, and an ordinary transmitter and receiver of any well known andl approved type. Then a connection is eX- tended `trom a calling` station to an idle loud speaking station conversation may proceed immediately, no call bell being provided at the called station. The called station responds by simply speaking into the transmitter. The loud speaking receiver thus serves as a calling signal. Two talking circuits including three talking conductors are provided between a calling and called subscriber, each talking circuit including a transmitter and a receiver. 1f the called line is busy, a busy tone is automatically connected to the called line for indicating the busy condition to the calling subscriber. The simple restoration of the receiver to the switch hook at the calling station releases the established connection.

Referring to the accompanying drawing which illustrates one embodiment of the in vention there is shown a calling substation O connected by means of three conductors to a non-numerical switch F at a central. ollic'e. Accessible to the non-numericalY 2, 1920. sei-iai no. 427,827.

switch F is a connector switch C which. is adapted to be directively set under the control of the impulse sender S at the calling station C. At L there is shown a loud speaking station comprising a transmitter and a loud speaking receiver, The transmitter and loud speaking receiver may be et types well known in the art.

`W ith this description ot the elements, it is thought that the invention will be more iully understood by reference to the ollowing detailed description of the operation.

A party at station C. desiring to talk to a person who may be in the vicinity of a loud speakingv station L, removes the rcceiver from the switch hook 2 whereupon line relay 14;, individual to the station C, is energized and causes the operation of the non-numerical switch F thereby extendingT the line of station C to an idle connector switch C. rlhe non-numerical switch F may be a line finder such as shown in my Patent No. 1,193,137 issued August l, 1916. Referring to Fig. 1 of said patent the terminal 132, brush 133 and conductor 1311 correspond to terminal 9, brush 13 and conductor 80, respectively. Release conductor 123 of said patent corresponds to release conductor 81 of the present application. To adapt the finder et the said patent to the system ot the present invention, it is necessary to add the terminal 8 and brush 12 to provide `tor the additional lowormost talk- .ing conductor 82. Assoon as the callingline is extended through to the connector C, cutoii relay 15 operates and disconnects the line relay 14 as described in detail in said patent. Line relay 20 of the connector switch C is energized when the finder connects with the calling line over a path eX- tending` from grounded battery, left hand winding et relay 20, brush 12 and terminal 8 et switch F, transmitter 1, receiver hook 2 andcontact 3 thereof. impulse sender S, terminal 7, brush 11, side switch arm 51 in its first position and right hand winding of relay 2O to ground. Relay 20, in operating, completes an obvious circuit for slow-to-release relay 21.

The party at station O may now operate the sender S for the purpose of setting the selector switch C upon the terminals of the desired station L. It will be assumed that the number of the desired station is 24. The party at station O will lrst dial the llt digit 2 thereby7 causing two interruptions of the circuit oi relay 29. ln response to the first interruption ot the circuit, relay 22 will be operated over a path extending from ground, armature and back contact ol" relay 20, right hand armature and front Contact of relay 21 and winding of relay 22 to grounded battery. Relay 22, in operating, completes an obvious circuit for slow-to-release relay 24. Ylielay 24, in operating, completes an obvious circuit :tor escape magnet 25. Relays 21, 22, and 24 are preferably ot the slow-to-release type so as to maintain their armatures attracted during the transmission of the impulses of a series.

ln response to each interruption of the circuit of line relay 20, primary magnet 23 is energized over a path extending 'from ground, armature and back contact off relay 20, right hand armature and iront contact of relay 21, side switch arm 53 and its rst contact and winding of primary magnet 23 to grounded battery. in response to the two impulses transmitted to the primary magnet 23, the brushes 40 to 43 inclusive oit connector switch C will be moved two steps in their primary movement.

As soon as the last impulse of the tens series has been transmitted to the line relay 20, the circuit tor relay 2O will be closedv for a relatively long interval thereby interrupting the circuit for, and causing` the res lease oit, slow-to-release relay 22. Relay 22 in rctracting its right hand armature releases slow-to-release relay 24 which in turn opens the circuit for escape magnet 25. cape magnet 25 is designed so as to more the side switch arms 50 to 53 inclusive ot the connector switch C one step upon its deenergization so that said side switch arms are moved into their second positions.

The operator now dials the digit 4 thereby causing :four interruptions of the line.

circuit. rlhe line relay 20 thereupon re-x tracts its armature four times. Upon the lirst retraction in response to this series ot' impulses, slow-to-release relays 22 and 24 and escape magnet 25 are, in turn, succes sively energized. rllhe secondary magnet 26 will be energized each time relay 2O retracts its armature over a path extending from ground, Varmature and back contact of relay 20, right hand armature and front contact of relay 21, side switch arm 53 and its second contact, winding of magnet 26 to grounded battery. The brushes 40 to 43 inelusive are thereupon brought to rest upon the terminals 44 to 47 inclusive of the station L.

As soon as the last impulse of the units series ot impulses has been delivered to the relay 20, the circuit of relay 2O will remain closed thereby causing the release of slowto-release relays 22 and 24 and in turn Yescape magnet 25. Escape magnet 25,4 in de energizing, nieves brushes 50 to 53 inclusive :trom their second to their third positions.

The party at the calling station may no w talk over the established connection and it the called party is within hearing distance of the loud speaking receiver 49, he may respond, without actuating any mechanism at his station, by talking into the transmitter 48 thereby notifying the calling station ci' his presence. The transmitter 48 is prefer ably of the sensitive type in order that the called party may act'uate it by speaking from a distance, if desired. lfallring battery for the calling` station is supplied through the left hand winding of relay 20, brush 12, and terminal 8 oi' switch l?, trans mitter 4, receiver switch hoolr 2 and contact- 3 thereof, impulse sender S, terminal 7 and brush 11, side switch arm 51 and its third Contact, brush 41 and terminal 45 oi con. nector switch C, receiver 49. terminal 46, brush 42, third contact of side switch arm 52 and side switch arm 52, through the right hand winding of relay 2O to ground. In providing condenser @1in one of the talking conductors, a series circuit for direct current is provided through the calling transmitter and the called receiver and a circuit for operating the impulse relay 20 to control the movement of the switch is also provided. The called subscribers transmitter is sugplied with talking battery over a path eX- tending from negative pole of battery B, sidev switch arm 5() and its third contact, brush 40 and terminal 44 of switch C, transmitter 48, terminal 45 and brush 41, third contact of side switch arm 51, and the right hand winding of induction coil 60 to posi tive pole of battery B. Although various batteries including the battery B are shown on the drawing it will be understood that they have been shown only to simplify the drawing and that a common central rbattery is used. rllhe called subscriber in respond ing affects the transmitter thereby setting up currents in the primary winding ot induction coil 60 which are induced into the secondary of said coil and traverse brushes 10 and 11 and terminals@ and 7 of switch F and the receiver 1.

At the conclusion of the conversation, .the calling subscribe-r restores the receiver 1 to the switch hook 2 thereby opening the circuit or line relay 20. Relay 20, in deenergizing, releases relay 21 and causes the completion of a circuit Jfor release magnet 29 over a path extending from grounded battery, winding of magnet 29, Aoil normal contact 30 of switch C, backcontact and 'right hand armature ot relay 21 and back contact and armature of relay 2O to ground. Magnet 29, in operating, locks through its own contacts and causes the release of the switch C in the manner well known in the art. Relay 21 in retracting its left armature Utl causes the release ot the line linder l?, which switch opens the circuit ot eut-olif relay 15, as described. in detail in said patent. As soon. as the connecter switch C returns rto normal, the locking circuit 'for release mag net 2f) is opened.

lt the called line had been busy, ground potential would have been present upon terminal l? ot the called station and betere the relay 2 would have deenergized, relay 2T would have operated and would have connected busy tone to the calling party at station C tor the purpose of informing him ot the busy condition of the called station. The path tor the energization of relay 2'? may be traced as follows: grounded battery Winding oi relay 27, front contact and lett hand armature of relay 2d, back contact and lett hand armature of relay 22, brush 43 and terminal et? of switch C to ground. Relay 27, in operating, locks through its inner right hand contact to ground at the front Contact and leit hand armature of relay 2l. The path for the busy tone from the source 28, extends through the lett hand armature and :front contact of relay 27, and through condenser 3l to the calling line.v As soon as the relay 2'? operates, release magnet 29 operates over a path extending from grounded battery, winding of magnet 29, contacts 30, and outer right hand armature and front contact of relay 27 to ground. Magnet 29 in operating locks and causes the return ot the switch C to normal. Relay 27 'remains operated until the calling subscriber hangs up and releases relays 20 and 21. The releasing' operations takes place upon the restoration of the receiver as described in connection with a successful call.

What is claimed is:

l. In a telephone system, a. telephone station having an ordinary transmitter and a receiver, an impulse sender thereat, a telephone station comprising a loud speaking receiver and a sensitive transmitter, and means including an automatic switch adapted to be set under the control ot said sender for simultaneously establishing a plurality of conversational circuits between said stations, said circuits each including a transmitter and a receiver.

In a telephone system, a calling telephone station, an impulse sender thereat, a called station including a loud speaking receiver and a sensitive transmitter, and means including an automatic switch for establishing a pair oi' conversational circuits between said stations, said circuits each including a transmitter and a receiver.

3. ln a telephone system, a calling station comprising a transmitter and receiver, a plurality of stations, each comprising a loud speaking receiver and a sensitive trans* mitter, an automatic switch, and an impulse sender at the calling station for controlling said switch to connect the calling station with another station, said connection including a pair of talking circuits one of said talking circuits including the receiver and the sensitive transmitter and the other of said circuits including the transmitter and the loud speaking receiver.

4. ln a telephone system, a plurality of calling stations, called stations, three conductors extending from each of said stations to a central point, automatic switches at said central point for said conductors, a circuit or setting said automatic switches including two of said three conductors in series to establish a pair of conversational circuits between the calling and called stations formed by said three conductors.

In witness whereof, I hereunto subscribe my name this 23rd day of November A. D.,

CHARLES L. GOODRUM. 

